The present invention relates to mechanically encoding of keyboards, and more particularly, the invention relates to keyboards of the type wherein the depressing of a key displaces bodies in a matrix of intersecting row and column channels.
Keyboards of the type to which the invention pertains are disclosed, for example, in U.S. Pat. No. 3,845,255, and also in German patent application No. 25 36 043. These publications disclose also contact springs at the ends of the channels for actuation by the displaced bodies, e.g. balls. The German patent application discloses particularly that the contact springs are fastened to the structure of the board containing the channels for the balls. Such a structure is basically sound but is disadvantaged from a point of view of assembly. The contact springs and their connection to conductors for signaling the state of the contacts have to be properly adjusted and tested, but these operations can be carried out only after the contacts have been inserted and mounted to the keyboard support structure. Consequently, it was found necessary in cases to take out some of the contacts or to rewire a portion of the interconnect circuitry. If additional circuit elements are present, the installation, testing, and possible replacement is even more complicated, and may readily require partial disassembly of the keyboard.